Texas Star DX 667V Max PEP Drive Power

[nomadradio]

AMC is automatic modulation control,

AKA modulation limiter. Most likely already turned up to max. Or maybe even has the "wide open" truckstop mod, removing the limiter transistor altogether. When this happens, turning the modulation control trimpot has no effect.

Somebody needs to come up with a comptibility tool for this situation. It's a story as old as solid-state linears. Radio too big, amplifier input limit too small.

A box with an attenuator in it and coax sockets to feed in and back out would also cut down the receiver's signal level. Giving the box a relay to allow a direct connection for receive and knock down the transmit power to half or one third would solve this kind of problem.

And bypassing the driver would as well. That radio is the perfect size to drive four 2SC2879 transistors directly. Would sound better, too.

It's time somebody posted a step-by-step "how-to" for this procedure. Would take one for each version, though. Been more than one 667 version over the decades.

73


73

 

[AK #5]

Not the AM carrier, AMC is automatic modulation control, a VR on the board that limits peak modulation.
Try this, put the radio on a wattmeter and slowly reduce the microphone gain while talking and note the result on pep.


73
Jeff

Ok will do.

 

[AK #5]

AKA modulation limiter. Most likely already turned up to max. Or maybe even has the "wide open" truckstop mod, removing the limiter transistor altogether.

I gave specific instructions to NOT remove any limiters when I bought it. So it should still be there. I bought it from Trucks CB and they usually do a good job in doing what the customer requests.

I will get in there and turn down the power at some point, if I can't get the desired result by turning down the mic gain.